There are many situations where it is required to provide a structure or the like with captive nuts such that a system can be assembled in place and/or such that components may be fastened to the structure. To satisfy this need blind rivet nuts, commonly referred to as “rivnuts”, are often used and installed into a structure. This is especially true in situations where access to only one side of the structure is accessible. The inaccessible side may be referred to as or associated with a blind cavity.
A structure is typically preformed or drilled to have designated holes for the insertion of the rivnuts. The rivnuts are subsequently compressed using a mandrel or other rivnut installation tool such that they are crimped intimately around the periphery of designated holes, thus preventing withdrawal therefrom. In general, rivnuts have an inner threaded channel for the coupling of a threaded fastener, such as a bolt or screw, therein and thus the attachment of components thereon.
Rivnuts are often used, for example, on gyro structures including stabilized platform gimbal assemblies, which have blind inner cavities. The stated rivnuts are utilized for the attachment of wire harnesses to the gimbal assemblies. During certain maintenance, repair, modification, or update tasks of the gyro structures the wire harnesses are removed from the gimbal assemblies.
The wire harnesses are attached via cable clamps to the gimbals. The clamps are attached using screws. A locking compound, such as LOCKTITE®, is often applied to the screws prior to being threaded into the rivnuts to prevent loosening or dislodging of the screws. After an extended period of time and due to the use of the locking compound, when the screws are removed the threads within the rivnuts can be stripped or damaged. In certain instances, the removal of the screws causes the rivnuts to loosen relative to the structure and spin in the associated structure holes.
Spare gimbals for the replacement of the gimbals, that have one or more damaged rivnuts, are often scarce or nonexistant. Thus, the entire gyro associated stabilized platforms are unuseable and non-serviceable. Replacement of gimbals with newly manufactured gimbals is generally considered an undesirable option due to the high costs, part complexity of a gyro stabilized platform, and many times the lack of original manufacturing tooling associated with the gimbals.
It is also undesirable to drill out a rivnut. When drilling out a rivnut the lower inner portion of the rivnut breaks off and then resides within and cannot be removed from the blind cavity. The broken off portion is considered foreign object debris and can rattle within the cavity and cause noise or improper operation of gyro components.
Thus, there exists a need for an improved removal technique that allows for the extraction of a rivnut including the portion thereof that resides within a blind cavity.